The invention relates to a heat-resistant optical fiber and a method of manufacturing the same.
A previously known heat-resistant optical fiber is made of a conventional optical fiber comprising a core and a cladding and which has formed on the outer peripheral surface, a polyimide resin coating further having formed on its outer periphery, a metallic coating (see, for example, Japanese Unexamined Utility Model Application No. HEI6-82608(1994)).
Another known heat-resistant optical fiber is provided with a polyimide resin coating on the outer peripheral surface of the cladding and a carbon coating formed on the outer peripheral surface of the polyimide resin coating (see, for example, Japanese Unexamined Patent Application No. HEI 8-15585 (1996)).
A method of manufacturing a heat-resistant optical fiber is also known, wherein a metallic coating is formed on the outer peripheral surface of an optical fiber by means of the dipping method or the electroless plating method (see, for example, Japanese Patent No. 2567951).
Moreover, fixing the optical fiber is performed by use of plastic resin or ceramic resin having a smaller linear expansion coefficient (see, for example, Japanese Unexamined Patent Application No. 2004-125846).
A known optical fiber referred to by the term “grating fiber” comprises an optical fiber having a photo sensitive core which is provided on the outer peripheral surface with a covering made of ultraviolet-curing resin, silicon resin or carbon, and is also provided at a part of the core with a grating part by applying light from sidewise of the covered optical fiber (see, for example, Japanese Unexamined Patent Application No. HEI 10-82919 (1998)).
Furthermore, there is known to public a technology using an optical fiber fitted into a stainless capillary in order to provide an intrusion detection line which an intruder breaks to thereby cause the intrusion to be detected (see, for example, Japanese unexamined patent application 2000-306167).
Another conventional technology uses an optical fiber fitted into a stainless capillary in order to provide a strain detection line for monitoring strain of bedrock or structures (see, for example, Japanese Unexamined Patent Application No. HEI 10-197297(1998)).